Method of making printing-plates.



M. A. DROITGOUR.

METHOD OF MAKING PRINTING PLATES.

APPLICATION TILED MAY 26, 1910.

1,064,134, Patented June 10, 1913.

2 SHEETS-SHEET l.

WITNESSES INVENTOR coLuMluA PLANOORAPII c0., WASHINGTON. D. C.

Fig: 2.

M. A. DROITCOUR.

METHOD OF MAKING PRINTING PLATES.

APPLICATION FILED MAYZB, 1910.

1,064,134, Patented June 10, 1913.

2 SHEETS-SHEET 2.

0mm mam 36 j sfi: Mr /42 4.4 24 AM 0 W $40 4/ mvsuTTi WITNESSES I w 7km/wa M MICHAEL A. DROITCOUR, OF OAK PARK, ILLINOIS.

METHOD OF MAKING PRINTING-PLATES.

Specification of Letters Patent.

j fatented Jime 1.0, 11913.

Application filed May 26, 1910. Serial No. 563.617.

To ((7! 70710727475 may concern.

lie it known that I, ltltormnr. A. Dnorr- ((HIR, a resident of Oak Park,in the county (it (look and State of Illinois, have invented a new anduseful Improvement in it'iethods of linking Printing-Plates, of whichthe following is a specification.

This invention relates to a method of making printing plates fromcelluloid or other plastic substances. 7

The object of the invention is to provide a method of making such plateswhereby the plates are made of uniform thickness througlmut so that it.will not be necessary to shave or otherwise treat the rear face thereofin order to make the same even, smooth, and of uniform thickness.

The invention, generally stated, consists in pressing the material whilehxated into a matrix between rigid flat plates or pressure surfaceswhich are positively guided so as to press the plastic material. down touni form thickness tl'iroughout, and. while so pressing the plateexhausting the air from the space between the pressure plates and thecelluloid sheet and other parts so as to prevent the trapping o'l. airbubbles in any part which would render the plate nonuni'lorm inthickness.

in the accon'ipanying drawings I have shown a press suitable forcarrying out the method.

In said drawings Figure 1 is a side elevation partly broken out of apress embodying my invention; Fig. 2 is an end elevation of the same;Fig. 53 is a horizontal section on the line 3 I), Fig. 1; Figs. 4- and 5are en larged detail vertical sections through the hollow press plates,taken respectively on the lines l-4t, Fig. 1 and 5, .Fig. 3; and Fig. 6is an exaggerated sectional view illustrating the ett'ect ot themake-ready.

The press illustrated in the drawings comprises a suitable base 1, heador upper pressure member 2, a table or lower pressure member 3, andsuitable connections and actuating mechanism. The pressure members 2 and3 are perfectly rigid and are arranged jt'or relative approximation andseparation in exact parallelism to each other. It is obvious that eitheror both of said members may be movable. As shown, the lower member ismovable and the upper member stationary. To this end the upper member orhead 2 and base 1 are connected by the tie rods or columns 4, which fitin notches in the edges of said head and base, are held therein by meansof removable caps 13, and are provided on their ends with heads or nuts7. all as will be readily understood without detailed description.

The lower pressure member 3 may be re- (-.i1')rorated vertically by anysuitable mecha- .nism. As shown bearing against the lower :laee ofsaline member are shoes 9 provided with concave seats tor receivingcircular pins 10 which rest in similar seats in the arms of lever 11,which are fulcrumed on suit: .ble standards 12 by means 01'' thecircular pins 13 fitting concave seats in said levers and standardsrespectively. The in ner ends oi. the lovers are provided with concaveseats resting upon the pins it which in turn rest upon the piston 15 ota suitable power cylinder 16 secured to or formed in the base i. andprovided with suitable valve controlled inlets and outlets for thepressure medium, which may be either compressed air or water, preferablythe former. The arrangement shown gives a very powerful upli'lt to thelower pressure member 3, in exact parallelism to the press head, butgives only a limited stroke or travel.

Cooperating with the upper and lower pressure members are suitablehollow plates marked 18 and 19 respectively, which are substantiallyduplicates of each other, and which constitute the platens or pressurefaces of the press between which the matrix and the plastic sheet arepressed to form the printing plate. These platens are hollow in order tohave admitted thereto steam for heating and rendering plastic thecelluloid sheet, and also to have admitted thereto water for the purposeof cooling the same when the pressing is finished. Any form of hollowplates or platens will answer the purpose. Those shown are of specialbuilt up construction but this is not essential, as they may be coredout castings. They are preferably brass and of light construction inorder to quickly heat and cool when the steam and water respectively areadmitted thereto. It is not necessary that they have any great strength,as they are backed by the rigid 'n'essiilre men'lbers, which preventthem 'lrom being strained or getting out of true. Their faces areperfectly smooth and flat and true, and they must have sutiicientstrength not to collapse or yield under the pressure. The lower platenrests loosely on the lower pressure member so that it can be readilyshoved into the press and pulled out, which is necessary, as the pressdoes not open sutficiently for the convenient placing and adjustment ofthe work between the pressure members. The upper platen, however, mustbe attached to the press head. This may be done in various ways. Asshown, the platen is held by means of bolts 20 extending through thelugs on the platen and into the press head. A table 21 with its top on alevel with the top of the lower pressure member when in its lowermostposition is provided for receiving the bottom platen when the latter iswithdrawn from the press to receive the work or permit its removal whenfinished. This table may be secured to the press frame, but is shownsecured to the lower pressure member 3.

For the admission of steam and water to the hollow platens or pressureplates they have connected thereto pipe members 24 leading to trunks orheaders 25, which in turn have connected thereto the supply and exhaustpipes. The connections to the lower or movable platen include the pipemembers 26 and 27 connected by swivel joints and so arranged as topermit vertical and lateral movement of the platen without breaking theconnections, so as to permit the platen to be moved into and out of thepress, as will be readily understood. The pipe connections on one sideof the press are provided with two supply branches, to wit, a branch 28for steam and a branch 29 for water, while the pipe connections on theother side of the press are provided with two exhaust branches, to wit,a branch 30 for the water leading to a sewer or the like, and a branch31 for the exhaust steam leading to a steam trap or the like. One of thepresser plates or platens, such as the upper presser plate or platen 18,is also provided with a horizontal tapped hole 32 communicating with avertical hole 33 which leads through said plate to the space between thetwo presser plates. To the hole 83 is connected a pipe or hose member34L which leads to a suitable source of vacuum, such as a suction pumpor a reservoir or tank in which pressure less than atmospheric pressureis maintained. During the pressing operation the matrix and plasticsheet are entirely inclosed in an air tight chamber from which the airis exhausted through the connection 34. This is ettected by providing aseal such as a rubber or similar ring or wall 35 between the twopressure members, said sealing member being shown as supported on aflange 36 on the lower platen 19 and surrounding the presser facethereof and arranged to contact with the top platen and of sufiicientheight so that when the platens are nearly closed this rubber seal iscompressed to provide a sealed chamber in which the work is inclosed.The rubber ring or wall does not contact with the work, but the edges ofthe latter are entirely clear so that the air can readily escape frombetween the matrix, celluloid sheet and other parts. The pressing iseffected while exhausting air from the chamber, thereby preventing theaccumulation of air between the matrix and celluloid sheet or betweenthe celluloid sheet and presser plates or platens, and preventing thetrapping of air which would cause bubbles and unevenness of thecelluloid sheet or plate.

In carryingout the method by the foregoing or any other suitableapparatus the matrix 10 with a make-ready 41, it the plate is to be forhalf tone or other high grade printing, and the celluloid sheet or plate42 are assembled either side up, upon the platen 19 while the latter ison the table 21. The seal 35 is then placed on the platen and the wholeshoved into the press. The cylinder 16 is then actuated to elevate thelower pressure member 3. A slight approximation of the presser plates orplatens puts pressure upon the rubber ring 35, thereby absolutelysealing the space inclosed thereby. The connection 3a to the vacuumproducing apparatus or means is then opened so that the air in the spacebetween the presser plates or platens and the rubber ring 35 is reducedbelow atmospheric pressure, thereby withdrawing the air from between theseveral sheets comprising the work and also between the presser plate orplaten andthe celluloid sheet so that in the pressing of the parts airbubbles are not trapped between the presser plate and the celluloidsheet. The steam connections to both platens are also opened in orderthat the presser plates or platens may be heated to soften the celluloidand render it plastic. After a suthcient length of time, about 90seconds, the celluloid sheet is sutficiently plastic and the press isthen fully closed by admitting more fluid to the cylinder 16 and thecelluloid is pressed well into the matrix. The steam then shut ott andwater admitted to the hollow plates to cool the same and harden or setthe celluloid plate. When sutliciently hardened the water connectionsare closed, the cylinder 16 released, and the lower platen pulled out ofthe press in order that the printing plate can be readily removed and afresh sheet put in place. During the entire time of pressing the work isin a chamber under less than atmospheric pressure.

For high grade printing those portions ot the plate-face which are togive the solid parts of the impression must be higher than thoseportions which produce the high lights of the impression. These resultsare secured in my method by underlaying the matrix at the points wherethe ligl'it portions of the plate are derived, by the make-ready 11which is so built up as to have the greatest thickness at the pointswhere the high lights are to be most pronounced. This underlay elevatesthe face of the matrix at those points, as at 44, so that when thecelluloid sheet is pressed into the matrix said sheet will be thinnerat. those points. (lonsequently, the celluloid plate will have its faceof varying heights, as desired, but at the same time its back, onaccount of the positive pressure of the flat rigid platen, is perfectlysmooth and flat so as to dispense with shaving or other operation torender the back smooth and even, as is the case where a yieldingpressure element or medium is used. A more perfect plate is also formed,as the shaving operation does not always produce regularity inthickness. The preferred make ready is made up of varying thicknesses ofpaper sheets and is secured as a whole to the back of the matrix bypasting at the corners only.

The presser plates or platens have absolutely [lat faces and the pressis so coir strueted that these tlat faces are brought together inperfect parallelism to each other. Consequently the celluloid sheet isgradually formed to uniform thickness from end to end and side to side,thereby giving a plate which is more perfect than when made by lluidpressure acting directly upon the face of the celluloid as hasheretofore been proposed. The absence of all air bubbles between thepresser plate and platen and the celluloid sheet leaves the back of thecelluloid plate perfectly flat. As a consequence celluloid plates can bemade by this process so perfect that they do not need to be ground orshaved off on the back in order to render the same smooth and even.

The process is intended primarily for making printing plates fromcelluloid, but obviously it is adapted for making such plates from othersuitable plastic material.

hat I claim is:

1. The method of making printing plates from substances which can berendered plastic, consisting in inclosing the plate forming material andmatrix in a sealed space, exhausting air from said space, and whileexhausting air from said space foreing the plate forming material intothe matrix by means of rigid pressure surfaces contacting directly withthe matrix and plate forming material and having movement ofapproximation in perfect parallelism.

9. The method of making printing plates from celluloid consisting ininclosing a sheet of celluloid and a matrix in a sealed space,exhausting air from said space, applying heat to soften. the celluloid,While oxhausting air from the space forcing the celluloid sheet into thematrix by means of rigid pressure surfaces contacting directly with thematrix and celluloid sheet and by presing the plastic substance into thematrix by direct contact of rigid pressure suritaces having movement ofapproximation in per foot; parallelism, and simultantamsly therewithholding the same under partial vacuum to remove the air and gases frombetween the plastic substance, the matrix, and the )ressure elen'ients.

t. The method of making printing plates from substances which can berendered plastic, consisting in pressing the plastic substance into amatrix by direct contact of rigid pressure surl'accs acting normal tothe matrix face and having movement of approximation in perfectparallelism, and simultaneously therewith holding the same under partialvacuum to remove air from between the celluloid sheet and the pressureelement.

5. The metlmd of making printing plates consisting in taking a celluloidsheet, simultaneously heating the same and pressing the same into thematrix by means of direct contact of rigid pressure surfaces actingnormal to the matrix face and having movement of approximation inperfect. parallelisni, and simultanmuisly therewith holding the sameunder partial vacuum to remove the air from between the celluloid sheetand the pressure element.

(3. The method of making printing plates consisting in pressing in ascaled chamber having a pressure less than atmospheric a plasticsubstam'e by means of a member with a flat surfam: against the back ofsuch substai'ice into a matrix underlaid with reverse make-ready,thereby providing tones in the face of the printing plat andsimultaneously providing such plate with a llat back, substantially asdescribed.

7. The method of making printing plates consisting in pressing in asailed chan'iber having a pressure loss than atmospheric a sul'istancecapable of being rendered plastic by means of a member with a flatsurface against the back of such substance into a matrix underlaid withreverse make-ready and sitnultaneously heating such substance to renderit plastic, thereby producing tones in the face of the printing plateand sinniltaneously providing the latter with a flat back, substantiallyas described.

8. The method of making a printing plate from a plastic substance in asealed chamber consisting of pressing such substance by means of amember with a llat surface against the back of such substance into amatrix underlaid with reverse make-ready and simultanmmsly withdrawinggaseous contents from said chamber, thereby produc ing tones in the faceof the printing plate and at the same time providing such plate With aflat back, substantially as described.

9. The method of making printing plates in a sealed chamber consistingin pressing a substance capable of being rendered plas tic by heat, bymeans of a member with a flat surface, against the back of suchsubstance into a matrix underlaid with reverse make-ready,simultaneously heating such substance to render it plastic andsimultaneously withdrawing gaseous contents from said chamber, therebyproducing tones in the face of the printing plate and at the same timeproviding such plate with a flat back, substantially as described.

10. The method of making a printing plate in a sealed vacuum chamberfrom a substance capable of being rendered plastic by heat, consistingin pressing such substance by means of a member with a flat surfaceagainst the back of such substance into a matrix underlaid with reversemake-ready, simultaneously heating such substance to render it plastic,and subsequently cooling the printing plate thus produced, therebyproducing a toned printing face in said plate and at the same timeproviding such plate with a flat back, substantially as described.

11. The method of making a printing plate in a sealed vacuum chamberfrom a substance capable of being rendered plastic by heat, consistingin pressing such substance by means of a member with a. flat surfaceagainst the back of such substance into a matrix underlaid with areverse makeready, simultaneously heating both sides of such substanceto render it plastic, and subsequently cooling the printing plate thusproduced, thereby producing a toned printing face in said plate and atthe same time providing such plate with a flat back, substantially asdescribed.

12. The method of making a printing plate in a sealed vacuum chamberfrom a substance capable of being rendered plastic by heat, consistingin pressing such substance by means of a member with a flat surfaceagainst the back of such substance into a matrix underlaid with reversemake-ready, simultaneously heating such substance to render it plastic,and subsequently cooling both sides of the printing plate thus produced,thereby producing a toned printing face in said plate and at the sametime providing such plate with a fiat back, substantially as described.

13. The method of making printing plates from substances which can berendered plastic, consisting in forming a suitable matrix, applying tothe back of the matrix at the desired points underlays or a make-ready,then pressing a blank of the plastic material into the face of thematrix by means of rigid pressure surfaces acting normally to the matrixface and having movement of approximation in perfect parallelism,whereby a plate with a flat even back and with a make-ready face is produced, and holding the plate under such pressure until the plasticmaterial is set, substantially as described.

let. The method of making printing plates from substances which can berendered plastic, consisting in forming a suitable matrix, applying tothe back of the matrix at the desired points underlays or a make-ready,then pressing the plastic substance into the matrix face by directcontact of rigid pressure surfaces acting normal to the matrix face andhaving movement of approximation in perfect parallelism, andsimultaneously therewith holding the same under partial vacuum to removethe air from between the plastic substance and the pressure element,substantially as described.

In testimony whereof, I have hereunto set my hand.

MICHAEL A. DROITCOUR.

Witnesses E. HAssMANN,

E. TV. WINTER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of JPatents, Washington, D. G.

